Correct Answer: B

Rationale: If Gerald can bake 3 dozen cookies in 30 minutes, then he can bake 1 dozen cookies in 10 minutes (30 minutes / 3 = 10 minutes). To bake 12 dozen cookies, it would take him 120 minutes (12 dozen x 10 minutes = 120 minutes), which is equivalent to 1 hour and 40 minutes. Choice A (90 minutes) is incorrect because it does not account for the correct proportion of cookies baked. Choice C (2 hours) and Choice D (4 hours) are incorrect as they overestimate the time required based on the given information.

Correct Answer: C

Rationale: To add 4â…” and 6½, we first need to convert the fractions to have the same denominator. Converting 4â…” to 6ths gives us 8/6, and 6½ to 6ths gives us 7/2. Adding them together gives 15/2, which simplifies to 7½ or 9â…™. Therefore, the correct answer is 9â…™. Choices A, B, and D are incorrect as they do not represent the correct sum of the fractions after conversion and simplification.

Correct Answer: D

Rationale: To find the product of 12 and 15, you simply multiply them together. 12 multiplied by 15 equals 180. To express 180 as a decimal, you divide by 100. Therefore, the correct answer is 1.8. Choices A, B, and C are incorrect as they represent values that are not the correct result of multiplying 12 by 15 and converting it to a decimal.

Correct Answer: B

Rationale: If Gerald can bake 3 dozen cookies in 30 minutes, then he can bake 1 dozen cookies in 10 minutes (30 minutes / 3 = 10 minutes). To bake 12 dozen cookies, it would take him 120 minutes (12 dozen x 10 minutes = 120 minutes), which is equivalent to 1 hour and 40 minutes. Choice A (90 minutes) is incorrect because it does not account for the correct proportion of cookies baked. Choice C (2 hours) and Choice D (4 hours) are incorrect as they overestimate the time required based on the given information.

Correct Answer: B

Rationale: To find the number that 15 is 20% of, we set up the equation: x * 0.20 = 15. Solving for x, we get x = 15 / 0.20 = 75. Therefore, 15 is 20% of 75. Choice A, 3, is too small to be 20% of 15. Choice C, 75, is the result of the correct calculation. Choice D, 300, is too large to be 20% of 15.